I looked everywhere for a mattress pad (MP) of this quality. I was worried to buy one b/c my bed is a new pillow top so it is BIG. I was worried that a MP would change the feel and comfort of my bed especially if it was too tight. This pad has very stretchy sides and they go all the way around the corners and under the bed. It has never slipped out ( I¿ve had it 1 month) and it doesn¿t change the shape of the bed. It is MORE comfortable than before (if that is possible ¿). Very satisfied.